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For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 GMC K Sierra - 4WD 🢒 Transmission/Transaxle 🢒 Automatic Transmission - Allison 🢒 DTC P0561

Circuit Description

The transmission control module (TCM) requires a switched ignition voltage input and a direct battery voltage input.

DTC P0561 is a type C DTC.

Conditions for Running the DTC
    • The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
    • Engine speed is greater than 400 RPM for 0.5 second.

Conditions for Setting the DTC

DTC P0561 sets when the TCM detects a large variation in ignition voltage or battery direct voltage. When an ignition or battery direct voltage variation of 4.0 volts or greater is detected for 0.5 second, a fault pending is reported. After 1.0 second of 4.0 volts or greater variation, a DTC is set with a failure response.

Action Taken When the DTC Sets
    • The TCM does not illuminate the malfunction indicator lamp (MIL).
    • The transmission fails to hydraulic default.
    • DTC P0561 will be stored in TCM history.
    • The TCM inhibits torque converter clutch (TCC) engagement.
    • The TCM freezes shift adapts

Conditions for Clearing the DTC

A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
    • Inspect for aftermarket devices that could affect the operation of the starting and charging systems.
    • Inspect for the presence of aftermarket accessories, such as a remote starter, etc. Depending on how these aftermarket accessories are installed, they may interfere with the required voltage for proper operation of the transmission.
    • Inspect the wiring for poor electrical connections at the TCM. Inspect for the following conditions:
       - A bent terminal
       - A backed-out terminal
       - A damaged terminal
       - Poor terminal tension
       - A chafed wire
       - A broken wire inside the insulation
    • When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
    • You may have to drive the vehicle in order to experience a condition.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step observes battery feed.

    2.

  2. This step observes ignition failure.

    3.

  3. This step observes accessories for voltage fluctuation.

Step

Action

Value

Yes

No

Schematic Reference: Automatic Transmission Controls Schematics

1

Did you perform the Diagnostic System Check - Automatic Transmission?

--

Go to Step 2

Go to Diagnostic System Check - Automatic Transmission

2
  1. Install the scan tool.
  2. Turn ON the ignition, with the engine OFF.

    3. Important: Before clearing the DTC, use the scan tool in order to record the Freeze Frame and Failure Records for reference. The Clear Info function will erase the data.

  3. Record the DTC Freeze Frame and Failure Records.
  4. Clear the DTC.
  5. Start the engine and observe the charge indicator on the instrument panel cluster (IPC).

Does the charge indicator illuminate or the driver information center (DIC) display a charging system message?

--

Go to Charging System Test in Engine Electrical

Go to Step 3

3
  1. Turn the ignition OFF.
  2. Disconnect the TCM connector C1 (GRAY) at the TCM.
  3. Install the J 39700 breakout box and the J 43799 breakout box adapter at the C1 connector.
  4. Using a DMM, measure voltage at the C1 connector (GRAY), terminal 3, and a good ground.

Is voltage within the specified value?

B+

Go to Step 4

Go to Step 5

4
  1. Using a DMM, in sequence, measure voltage at the C1 connector (GRAY), terminal 2, and terminal 4, and a good ground.
  2. Turn ON the ignition, with the engine OFF.

Is voltage within the specified value?

B+

Go to Step 7

Go to Step 6

5

Test the battery positive voltage circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Diagnostic Aids

6

Test the ignition feed circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Step 9

7
  1. Start the engine.
  2. Operate all accessories. Refer to Checking Aftermarket Accessories in Wiring Systems.

Did voltage fluctuate by the specified value?

4 V

Go to Step 8

Go to Step 9

8

Determine the cause of the accessory voltage drop. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 10

Go to Diagnostic Aids

9

Important: In most cases, the TCM is not at fault. Investigate thoroughly before replacing the TCM.

Replace the TCM. Refer to Transmission Control Module Replacement .

Did you complete the replacement?

--

Go to Step 10

--

10

Perform the following procedure in order to verify the repair:

  1. Clear the DTC.
  2. Using the scan tool, monitor TCM voltage.
  3. Select Specific DTC.
  4. Enter DTC P0561.

Has the test run and passed?

--

System OK

Go to Step 1